SYNOPSIS

struct drm_connector_helper_funcs {
int (* get_modes) (struct drm_connector *connector);
enum drm_mode_status (* mode_valid) (struct drm_connector *connector,struct drm_display_mode *mode);
struct drm_encoder *(* best_encoder) (struct drm_connector *connector);
struct drm_encoder *(* atomic_best_encoder) (struct drm_connector *connector,struct drm_connector_state *connector_state);
};

MEMBERS

get_modes

This function should fill in all modes currently valid for the sink into the connector->probed_modes list. It should also update the EDID property by calling drm_mode_connector_update_edid_property.

The usual way to implement this is to cache the EDID retrieved in the probe callback somewhere in the driver-private connector structure. In this function drivers then parse the modes in the EDID and add them by calling drm_add_edid_modes. But connectors that driver a fixed panel can also manually add specific modes using drm_mode_probed_add. Drivers which manually add modes should also make sure that the display_info, width_mm and height_mm fields of the struct drm_connector are filled in.

Virtual drivers that just want some standard VESA mode with a given resolution can call drm_add_modes_noedid, and mark the preferred one using drm_set_preferred_mode.

Finally drivers that support audio probably want to update the ELD data, too, using drm_edid_to_eld.

This function is only called after the ->detect hook has indicated that a sink is connected and when the EDID isn't overridden through sysfs or the kernel commandline.

This callback is used by the probe helpers in e.g. drm_helper_probe_single_connector_modes.

RETURNS:

The number of modes added by calling drm_mode_probed_add.

mode_valid

Callback to validate a mode for a connector, irrespective of the specific display configuration.

This callback is used by the probe helpers to filter the mode list (which is usually derived from the EDID data block from the sink). See e.g. drm_helper_probe_single_connector_modes.

NOTE:

This only filters the mode list supplied to userspace in the GETCONNECOTR IOCTL. Userspace is free to create modes of its own and ask the kernel to use them. It this case the atomic helpers or legacy CRTC helpers will not call this function. Drivers therefore must still fully validate any mode passed in in a modeset request.

RETURNS:

Either MODE_OK or one of the failure reasons in enum drm_mode_status.

best_encoder

This function should select the best encoder for the given connector.

This function is used by both the atomic helpers (in the drm_atomic_helper_check_modeset function) and in the legacy CRTC helpers.

NOTE:

In atomic drivers this function is called in the check phase of an atomic update. The driver is not allowed to change or inspect anything outside of arguments passed-in. Atomic drivers which need to inspect dynamic configuration state should instead use atomic_best_encoder.

RETURNS:

Encoder that should be used for the given connector and connector state, or NULL if no suitable encoder exists. Note that the helpers will ensure that encoders aren't used twice, drivers should not check for this.

atomic_best_encoder

This is the atomic version of best_encoder for atomic drivers which need to select the best encoder depending upon the desired configuration and can't select it statically.

This function is used by drm_atomic_helper_check_modeset and either this or best_encoder is required.

NOTE:

This function is called in the check phase of an atomic update. The driver is not allowed to change anything outside of the free-standing state objects passed-in or assembled in the overall drm_atomic_state update tracking structure.

RETURNS:

Encoder that should be used for the given connector and connector state, or NULL if no suitable encoder exists. Note that the helpers will ensure that encoders aren't used twice, drivers should not check for this.

DESCRIPTION

These functions are used by the atomic and legacy modeset helpers and by the probe helpers.

AUTHORS

Jesse Barnes <[email protected]>
Intel Corporation,         
        

Initial version

Laurent Pinchart <[email protected]>
Ideas on board SPRL,         
        

Driver internals

Daniel Vetter <[email protected]>
Intel Corporation,         
        

Contributions all over the place

Lukas Wunner <[email protected]>

vga_switcheroo documentation

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